EF Core DateTimeOffset offset preserved instead of converted to regional time zone

Answer to the core question

EF Core does not convert a DateTimeOffset value to another time zone when you call SaveChanges or when the entity is materialized. The value that is sent to the database, and the value that comes back, contain the same Offset component that was supplied in the application code.

Why this is the case

• The datetimeoffset column type in SQL Server, the timestamptz type in PostgreSQL, and the text representation used by SQLite all store the offset as part of the value.
• EF Core’s default mapping for DateTimeOffset is a round‑trippable value converter that simply writes the value unchanged to the column and reads it back unchanged.
• Because DateTimeOffset already carries its own offset, DateTimeKind is irrelevant – the Kind property of a DateTimeOffset instance is always Unspecified, but the offset field is preserved.

When you might see a different result

• SQLite stores the value as a string; the SQLite driver may apply its own conversion logic depending on the connection string settings, so you should verify the actual stored text.
• If you register a custom ValueConverter that changes the offset (e.g., normalises to UTC), that logic will be applied on both write and read, but it is explicit and not automatic.

Practical steps for your scenario

1. Check the column type. In SQL Server the column should be datetimeoffset; in PostgreSQL it should be timestamptz; in SQLite it should be a string that contains the offset (e.g., 2026-10-18T01:47:03+02:00).
2. Do not register a converter. If you have a ValueConverter that changes the offset, remove it or make it round‑trippable.
3. Verify round‑trip. Insert a DateTimeOffset with a non‑UTC offset, call SaveChanges, then query the entity again and compare the Offset property. It should match the original value.
4. Use HasConversion only when you explicitly want to store a different representation (e.g., UTC). In that case, the converter must be invertible so change tracking continues to work correctly.
5. Keep provider‑specific nuances in mind: if you are using SQLite, test the driver’s behavior with your connection string settings.

When you need a regional offset

If your application logic requires that every DateTimeOffset be stored with a specific regional offset (e.g., +02:00), then you must implement a ValueConverter that forces that offset before saving and restores the original offset when reading back. This is an explicit step, not an automatic EF Core feature.

Ask for missing diagnostic detail

To tailor the recommendation exactly, could you confirm which database provider you are targeting? If you are using SQLite, the driver’s conversion rules can differ from SQL Server and PostgreSQL.